The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Gear changes in manual and dual clutch transmissions are generally achieved by a synchronizer clutch which is splined to and which rotates with an associated shaft. Adjacent the synchronizer clutch is one or a pair of gears which provide distinct gear or speed ratios. Axial motion of the synchronizer clutch first synchronizes and then couples the gear to the shaft and drive torque is then applied to the engaged gear or shaft.
Axial motion of the synchronizer clutch is commanded by a shift fork which engages a groove in the periphery of the clutch and which is slidably disposed on a shift rail. A linear output of a two or three position actuator may be directly connected to the shift fork or the shift fork may be secured to the shift rail, in which case the actuator is connected to and translates the shift rail.
Especially in the latter configuration, each shift fork requires a dedicated shift rail. Thus, in a five speed transmission which encompasses six gears with reverse, it is necessary to have at least three shift rails, actuators and shift forks. In a six or seven speed transmission (which encompasses seven or eight speeds when reverse is included), it is necessary to have at least four shift rails, actuators and shift forks.
Because each shift rail occupies space in the transmission and requires mounting bosses and/or linear bearings, they add to the complexity and cost of a transmission. Reducing their number is thus desirable.